A new study published in the Proceedings of the National Academy of Sciences points to a connection between happiness and longevity.
A study by University College in London of about 3,500 people found those who reported feeling happiest had a 35 percent lower risk of dying compared with those who reported feeling least happy.
A USA Today story on the research says in part:

Laura Kubzansky, an associate professor in the Department of Society, Human Development and Health, at Harvard’s School of Public Health in Boston, says there’s a “burgeoning body of work that suggests positive psychological functioning benefits health,” and this study is significant because it “adds to the arsenal.”
“It could say to people, you should take your mood seriously,” Kubzansky says. “I think people sort of undervalue emotional life anyway. This highlights the idea that if you are going through a period where you’re consistently distressed, it’s probably worth paying attention to how you feel — it matters for both psychological and physical health.”

Recently I’ve blogged about Martin Seligman’s definition of flourishing and Deepak Chopra’s formula for happiness.
This research gives one more reason to nurture your emotional well being — that is, if you want to live longer. Maybe there’s some research to be done connecting happiness with the will to live? If you’re unhappy, maybe you take worse care of yourself because you don’t see the point in prolonging your unhappiness?